Instruction manual

6–5
Principles of Operation
Printing Mechanism
While the principles of line matrix printing are easy to state, the act of
printing dots accurately from a rapidly oscillating shuttle onto a vertically
moving piece of paper requires precise timing and coordination between
printer logic and the printing mechanism. The printing mechanism consists
of the shuttle frame assembly, the ribbon transport system, and the paper
transport system.
Shuttle Frame Assembly
The central element of the printing mechanism is the shuttle frame assembly,
which houses the shuttle drive motor and the shuttle assembly. (See
Figure 6–5.) The hammer springs are grouped in comb–like assemblies
called frets, and seven frets are bolted to the hammer bank. The LG04
plus
hammer bank has seven 4–hammer frets, the LG08
plus
hammer bank has
seven 7–hammer frets, and the LG12
plus
hammer bank has seven 13–hammer
frets. The shuttle drive motor is built into the shuttle assembly casting and
drives a flywheel/crankshaft to which are attached two connecting rods. The
small end of one connecting rod attaches to the hammer bank, the small end
of the other connecting rod attaches to a counterweight frame surrounding
the hammer bank. (The hammer bank + the counterweight = shuttle
assembly.) The rotary motion of the shuttle drive motor converts to linear
and opposing motion of the hammer bank assembly and the counterweight,
in an arrangement similar to that of a horizontally–opposed piston engine.
Mechanically, this design achieves the same benefits as such an
engine—perfect primary balance, low vibration, and durability.
Hammer Bank
Counterweight
Shuttle Frame Assembly
Guide Shaft
Connecting Rod
Shuttle Drive Motor
Figure 6–5. Shuttle Frame Assembly